Although naltrexone has been available by prescription since late 1984, it has not been widely used in the treatment of opiate dependency. One reason for this has been the generally poor retention of patients on naltrexone. Although there are many potential reasons for poor retention, naltrexone's side effects are cited by both opiate addicts and researchers as an important factor. Some of naltrexone's induction side effects may be caused by antagonist-precipitated withdrawal from endogenous opiates. Because clonidine is effective in ameliorating opiate withdrawal symptoms, clonidine may also reduce naltrexone induction symptoms that are antagonist-precipitated. This application proposes a classical, double-bind design to examine the efficacy of clonidine in reducing naltrexone induction side effects. Following detoxification, one hundred and forty opiate abusers undergoing 28-day, inpatient treatment for opiate dependency at Merritt Peralta Chemical Dependency Recovery Hospital, a private, not-for-profit chemical dependency recovery hospital in Oakland, California, will be randomly assigned to receive either a clonidine transdermal patch or a placebo transdermal patch that is identical in appearance. Subjects will have the patch applied three days before naltrexone induction. The efficacy of clonidine in reducing naltrexone side effects during the first 7 days of naltrexone treatment will be compared between groups on the items and scales of the Profile of Mood States, Symptom Checklist-90, and an Opiate Craving Scale. The effect on short-term retention will be determined by the number of patients in each group who remain on naltrexone for 60 days after discharge from the hospital. The effect on drug use will be determined by follow-up evaluations at 30, 60, and 90 days after discharge. Naltrexone induction side effects may be particularly important in influencing a patient's retention on naltrexone, and reduction of naltrexone's induction side effects may increase the numbers of patients who can be effectively treated with naltrexone. Naltrexone is a treatment modality which could be rapidly introduced into existing medical treatment settings to expand treatment capacity for I.V. opiate abusers and could also possibly reduce the spread of HIV infection by reducing I.V. opiate use. Reduction of naltrexone induction side effects by using clonidine could result in better patient acceptance of naltrexone and wider use of naltrexone as a treatment adjunct for opiate dependency.